Handle edge cases in encryption

**Problem**
When working with services, the error messages could be more descriptive.

**Suggestion**
Improve error handling and add detailed error messages.

**Context**
This would help with debugging and maintenance.

No files, tests, or entry points are named. Start by locating the service encryption and error-handling paths, then identify the edge cases and current messages that need coverage. Done means the affected failures produce descriptive, consistent errors and tests document the expected messages.

Written by the indexing model from the issue text.